CAREER: The Role of Iron and Reactive Oxygen Species in the Oxidation and Fate of DOM in Natural Waters

本研究将确定铁在涉及DOM降解的光反应和暗反应中的直接和间接作用，并估计铁在决定这种降解是将C作为DOM从河流转移到海洋，还是将C完全氧化成二氧化碳释放到大气中的重要性。拟议的工作将促进我们对地球上暴露于氧气或阳光下的土壤碳退化的理解。在陆面扰动期间S面。这些知识将使科学家能够更好地预测北极永久冻土中C的命运，并通过教育和推广计划，使社会能够通过北极融化的积极反馈，更好地为可能加速的全球变暖做好准备。为了让代表性不足的学生参与科学，PI建议通过伙伴关系扩大教育基础设施，这将为提高教学和沟通技巧提供新的机会。PI将开发一个与她的研究相结合的地球和环境科学课程，以核心教育原则为基础，并与评估目标相结合。对课程开发的一项新贡献将是(1)教育模块的结合，这些模块可以“望远镜”？(2)通过微观绩效评估生成关于学生参与和学习的数据；(3)通过学生为自己的同龄人群体迭代改进模块来增强主动学习。这项研究将在阿拉斯加的北极地区进行，因为(1)湖泊、溪流和土壤水提供了强光和弱光、氧气、DOM和铁浓度的天然实验基质，(2)冻土中有大量的有机碳储存（至少是现在大气中碳含量的两倍），这些土壤正因全球变暖而迅速融化。通过实地调查和自然水域实验来验证机理假设，PI将回答两个主要的研究问题：(1)铁介导的反应是否有利于阳光和微生物将DOM完全氧化为CO2 ？(2)黑暗中铁介导的DOM氧化是否是DOM命运的重要决定因素？

Title: The role of iron and reactive oxygen species in the oxidation and fate of DOM in natural waters This study will determine the direct and indirect roles of iron in both light and dark reactions involving DOM degradation, and estimate the importance of iron in determining whether this degradation will shunt C as DOM down rivers to oceans, or fully oxidize C to CO2 released to the atmosphere. The proposed work will advance our understanding of the degradation of soil carbon exposed to oxygen or sunlight at Earth?s surface during land-surface disturbances. This knowledge will allow scientists to better predict the fate of C in arctic permafrost soils, and through an education and outreach plan, will allow society to better prepare for the potential acceleration of global warming through a positive feedback from the thawing Arctic. To engage underrepresented students in science, the PI proposes to expand the infrastructure of education through partnerships that will offer new opportunities to enhance teaching and communication skills. The PI will develop a curriculum in earth and environmental science integrated with her research, grounded in core education principles, and mapped to assessment goals. A novel contribution to curriculum development will be the combination of (1) education modules that ?telescope? in age-context and difficulty from K-12 to undergraduate to adult outreach levels, (2) data generation on student engagement and learning through micro-assessments of performance, and (3) enhanced active learning by iterative improvement of modules by students for their own peer groups. This research will be done in the Alaskan Arctic because (1) the lakes, streams, and soil waters provide a natural experimental matrix of both high and low light, oxygen, DOM and Fe concentrations, and (2) there are tremendous stores of organic C in frozen soils (at least twice the amount of C now in the atmosphere) which are rapidly thawing from global warming. Using field surveys and experiments on natural waters to test mechanistic hypotheses, the PI will answer two main research questions: (1) Do reactions mediated by iron favor the complete oxidation of DOM to CO2 by sunlight and microbes? (2) Is the iron-mediated oxidation of DOM in the dark an important determinant of DOM fate?